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Driveline slack

8K views 14 replies 9 participants last post by  Bobkennedy 
#1 ·
I can't seem to find any information on acceptable drive train play. My 2007 commander QT II 4.7 ,107000 miles, has vibration /clunk issues. I found I need front diff. bushings. I also feel / see 1/4 in. rotation of front drive shaft play before inside CVs move. about 1/2" between moving front drive shaft ,before motion at rear shaft U joint. probably Xfercase chain slack. I'm not quite ready for dealer to tell me I need $10,000 in repairs. It seems to me a drive train with 8 CV/U joints,2 splines & chain in Xfer case along with 3 differentials, might have some play in drive train, but I could be wrong. It has happened once or twice in my life. Thanks, Art.
 
#2 ·
I see you didn't get any replies on this, and I'm wondering the same thing so hopefully if I bump this thread it'll get answered.

I have a 120k on my 5.7 QDII Commander and I have a clunk at highway speeds when I let off the gas and when I reapply. Like you, I expect some play, but how much?

Sent from my Nexus 6P using Tapatalk
 
#3 ·
Take it to a drive shaft shop to see what they say. I have had front end problems, and was less than satisfied with the dealer. I was told my 06 XK was a classic car and no new parts available. I won't say how long I was with out my XK but none of the loaner cars they gave me will ever sit in in my driveway. A unhappy guy who has been a Jeep guy for 20 yrs. And yes if there is front to rear play, your ft drive shaft, it needs to have the CV joints repaired, (not a jeep repair) or just needs to have the entire drive shaft replaced (a jeep repair).
 
#4 ·
Me personally, I'd rather avoid taking it to the dealership for something I can repair myself, if I can find the tolerances at least. I was an ASE certified mechanic for 11 years, so I hate paying someone else to fix something I know I can do.
 
#5 ·
Expressing the play (or lash) in rotation as a distance can be confusing. If you're measuring that distance at the pinion shaft, a 1/4" is a huge amount of play, if you're measuring that distance at the edge of the tires, that's a tiny amount of play.


Driveshafts, there should be no, to almost no perceivable play in rotation. There is play in shaft length, cause the shafts are designed to change length as the suspension articulates up and down.
The differentials, from the spider gears in them, will have a bit of play, more than a few degrees but less than 10 or 15. A 1/4" at the outside edge of the yoke or driveshaft hub sounds about right.
The automatic transmission, is hard to tell and even harder with a xfr case, since their lash combines.
The XFR case, I don't really know the spec, I just know my NV140 (QTI) has more lash than I would expect. Like 1" or more at the driveshaft hubs. That might be normal, because the XFR case uses a chain and Sprague clutch.


The XFR case should let the front driveshaft spin faster than the rear (unpowered) that prevents the front axle from back- driving the drivetrain, which can cause instability and undesirable reactions. When the front axle slows down, the Sprague clutch grabs again and transmits power to the front again, you crest a hill and start rolling forward with the drivetrain back driving or engine braking the vehicle, as the front driveshaft tries to back-drive the drivetrain, the Sprague clutch will disengage and let it spin free NOT transmitting any power.


No, part time 4WD, that locks the front/rear driveshafts at the same speed doesn't have Sprague clutches, these effects aren't nearly as bad as the fact the front/rear driveshafts are locked at the same speed. Since Full Time 4WD has to drive around on paved roads at high speeds, NOT only do you need a differential in the XFR case, but also a Sprague clutch to disconnect the front drivetrain in back-drive situations, for smooth operation and keeping tires in contact with the paved surface. I don't know for a fact, but I imagine the QTII and QDII, when you go into 4LOW that locks the center differential, that likely also locks the Sprague clutch.
 
#6 ·
I am reviving this old thread. I have had a clunk in mine for a few months now. I got it on a lift today and there is a lot of slop in the drive line (transfer case).

How much is too much? It rattles around a lot when turning the drive shafts with my hands.

Is it toast? I have 145,000 miles on the old beast.
 
#7 ·
I am reviving this old thread. I have had a clunk in mine for a few months now. I got it on a lift today and there is a lot of slop in the drive line (transfer case).

How much is too much? It rattles around a lot when turning the drive shafts with my hands.

Is it toast? I have 145,000 miles on the old beast.
DB;

Have you ever replaced your front upper differential bushings?
 
#10 · (Edited)
Gator;

I honestly can't answer you intelligently about the amount of slop in your transfer case, because I really don't know and I won't be home until December 2nd where I could go out and check mine for a comparison.

Let me ask you, when are you hearing the clunks you're describing?

Shifting into gear, during acceleration & turning, or when you hit some bumps?
 
#12 ·
If that's the case, then that could very well have something to do with the slop in your transfer case and/or drive shaft play.

I know you like to tackle a lot of this stuff yourself, but, you may want to take your XK into a 4x4 shop, that deals with Jeeps regularly and get it checked out.
 
#13 ·
may be dawn good advise. I just helped my neighbor put in a car lift at his house this weekend. It was the first time I got under my Jeep in a while. I think it is the TC. Are those transfer cases chain driven? or gear driven? If it is chain I may be in luck, (at least easier to fix) if gears then It is toast.
 
#14 ·
Front output shaft is chain driven, planetary gears for Hi/Low. Looks like a you have to remove couple of dozen parts to get to the chain. I have not done this myself.
 

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